Electronic musical instrument with automatic bass performance circuitry

ABSTRACT

This invention provides an electronic musical instrument capable of carrying out bass performance conforming with chord performance by merely depressing keys in a keyboard for the chord performance. To this end, there are provided a chord detector for detecting the type of the chord including various notes, that is, root, fifth, major on minor third, and major sixth or minor seventh notes when the keys of the keyboard are depressed for chord performance, and bass selectors responsive to the outputs from the chord detector for selectively deriving bass tone signals corresponding to respective notes of the chord from tone generators and supplying the derived bass tone signals to respective bass gate circuits. The bass gate circuits are sequentially opened by timing pulses from a rhythm pattern pulse generator in a specific order conforming with chord performance, thereby providing automatic bass performance in a desired rhythm.

United States Patent Yasuji Uchiyama [72] lnventor 3,544,693 12/1970Tripp 8411.01 Hamakita,J apan 3,546,355 12/1970 Maynard. 84/103 [21]Appl. No. 115,681 3,548,066 12/1970 Freeman 84/103 [22] Filed Feb. 16,1971 3,567,838 3/1971 Tennes 84/101 [45] Patented 1971 PrimarExaminerLewis H M ers [73] Assignee Nippon Gakki Seizo Kabushiki Kaishay I k llamammsu shi,shizuoka ken Japan Assistant Examiner-Stan ey .1. 1towski Anome Fl nn& Fnshauf 321 Priorities Feb. 16, 1970 y y [33} Japan[31 45/12786; ABSTRACT: This invention provides an electronic musicalin- 16, J P b 45/127873 strument capable of carrying out bassperformance conform- 16, 1970,1998", 45/12788; P ing with chordperformance by merely depressing keys in a 1970 Japan 45/2717, keyboardfor the chord performance. To this end, there are provided a chorddetector for detecting the type of the chord including various notes,that is, root, fifth, major on minor [54] ET ZHE third, and major sixthor minor seventh notes when the keys of 6 Claims 12 Drawing g thekeyboard are depressed for chord performance, and bass selectorsresponsive to the outputs from the chord detector for 152] US. Cl84/l.03, selectively deriving bass tone signals corresponding to respec-84/l.24,84/D1G. 22 tive notes of the chord from tone generators andsupplying the [51 1 Int. Cl Gl0h l/00 derived bass tone signals torespective bass gate circuits. The [50] Field of Search 84/ 1.01, bassgate circuits are sequentially opened by timing pulses 1.03, 1.17, 1.24,DIG. 22 from a rhythm pattern pulse generator in a specific orderconforming with chord performance, thereby providing automatic [56]References cued bass performance in a desired rhythm.

UNITED STATES PATENTS 3,305,620 2/1967 Young 84/l.17

3 1 5 8 TONE CHORD KEYBOARD TONE 7 J GATE COLORIN GENERATORS g FILTER G'4 2 i C 13A 13B 8 GATE i SFGGFE S QEE CTOR L T LHEIB I GATE 1 14A'@ 1'3FILL TONE '11 BASS is COLORING T L 31 SELEHCTOR GATE I FILTER 8 15A (914 L 24 X EE CTOR 19 55115 m GATE 1 l X I l q 1 I I 9 i I PULSE TIMING i20 ENERATOR PULSE ENC.

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ELECTRONIC MUSICAL INSTRUMENT WITH AUTOMATIC BASS PERFORMANCE CIRCUITRYBACKGROUND OF THE INVENTION This invention relates to an electronicmusical instrument, and more particularly to an improved electronicmusical instrument wherein bass performance can be carried out in adesired rhythm pattern with or without accompanying chord performance bymere operation of the chord keyboard.

A conventional electronic musical instrument, for example, an electronicorgan, is usually provided with upper and lower manual keyboards and apedal keyboard. Generally, the melody performance is played by operatingthe upper keyboard with the right hand, the chord performance is playedby operating the lower keyboard with the left hand and the bassperformance is played by operating the pedal keyboard with the leftfoot. In such a case, it is necessary to perform the chord and bassperformances which are the accompaniments of the melody performance inconsonance with the melody performance. Further, the chord performanceshould be played rhythmically with the left hand in consonance with themelody performance whereas the bass performance should be played withthe left foot with a rhythm pattern different from that of the chordperformance. To play the bass performance it is necessary to depress, inspecific rhythm, the keys of the pedal keyboard corresponding to notescontained in the chord while the same chord is being played. In otherwords, for unskilled players, it is more difficult to play the bassperformance by the manipulation of the pedal keyboard than to play thechord performance. Thus, with the prior art electronic musicalinstrument, a considerable skill is required to carry out the chord andbass performance in conformity with the melody performance so that ithas been difficult for unskilled players to play electronic musicalinstruments.

SUMMARY OF THE INVENTION Accordingly, it is an object of this inventionto provide a novel electronic musical instrument capable ofautomatically carrying out a bass performance which is most suitable asthe accompaniment of the melody performance without relying uponcomplicated operations of a pedal keyboard.

Another object of this invention is to provide a novel electronicmusical instrument capable of carrying out a continuous chordperformance in a desired rhythm pattern by depressing the keys of amanual keyboard for only a short period of time.

According to this invention there is provided an electronic musicalinstrument comprising tone generators; a keyboard provided with keyswitches for selectively keying tone signals from the tone generators; achord detector including first, second and third detector matrixes fordetecting the root and fifth notes, the third note, and the major sixthor the minor seventh note contained in the chord being played on thekeyboard; first, second and third bass selectors responsive to theoutputs from the respective chord detectors for selectively derivingbass tone signals corresponding to respective notes included in thechord from the tone generators; a chord gate circuit supplied with tonesignals from the tone generators through the operation of the keyboard;first, second, third and fourth base gate circuits supplied with eachbass tone signals corresponding respectively to the root note, fifthnote, third note and major sixth or minor seventh note from the bassselectors; and a rhythm pattern pulse generator for applying timingpulses to the chord gate circuit for opening (conducting) the same inaccordance with a predetermined rhythm pattern and for supplying timingpulses to the respectively bass gate circuits to open the same in aspecific order proper to the chord being played.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I shows a block diagram of oneexample of the electronic musical instrument embodying the invention;

FIG. 2 shows a circuit diagram of the chord detector matrix shown inFIG. I;

FIG. 3 shows a partial circuit diagram useful in explaining theoperation of the chord detector matrix shown in FIG. 2;

FIG. 4 shows waveforms of control outputs for explaining the operationof the circuit diagram shown in FIG. 3;

FIG. 5 is a circuit diagram of one example of the bass selector shown inFIG. 1;

FIG. 6 shows a circuit diagram of the pulse distributor shown in FIG. 1;

FIG. 7 shows a block diagram of a modified embodiment of the novelelectronic musical instrument;

FIG. 8 shows a connection diagram of the pulse distributor shown in FIG.7;

FIG. 9 shows waveforms of input and output pulses of the timing pulseencoder shown in FIG. 7;

FIG. 10 shows waveforms of output pulses of the pulse distributor shownin FIG. 8;

FIG. 11 shows a schematic block diagram of another embodiment of thenovel electronic musical instrument; and

FIG. 12 shows musical notations useful in explaining the operation ofthe electronic musical instrument shown in FIG. I 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The electronic musicalinstrument shown in FIG. 1 comprises a chord keyboard 1 including aplurality of key switches 2 (only one of them is shown) operated byrespective keys (not shown) of the keyboard. As is well known in theart, when actuated by the associated key, the key switch 2 derives atone signal of the selected pitch from tone generators 3. The term chordkeyboard 1' is used herein to mean a lower manual keyboard in case ofthe electronic musical instrument including an upper manual keyboard anda lower manual keyboard as in a normal conventional electronicorgan, orto mean a lower half portion of a keyboard in case of the electronicmusical instrument being provided with only one manual keyboard. Thechord keyboard I is further provided with chord detector key switches 4(one of them is shown). Where the chord keyboard is a lower keyboard,the chord detector key switches 4 are provided for every key, whereaswhere a single keyboard is utilized for both melody performance andchord performance, the chord detector key switches may be provided forthe keys in the lower half of the keyboard which half being utilized forthe chord performance.

The tone signal derived from the tone generators 3 by closure of the keyswitch 2 is applied to a chord gate circuit 5 and the output from thechord gate circuit is converted into a musical tone signal having asuitable timbre through the function of a tone-coloring filter 6. Theoutput from the filter 6 is amplified by an amplifier 7 and thentransduced into audible sound by means of a loudspeaker 8.

Although not shown in the drawings, tone signals for the melodyperformance are also derived from the tone generators 3 by the operationof the upper keyboard or the higher half portion of a single keyboardand such tone signals are converted into musical tone signals by thefunction of a tonecoloring filter, the output thereof being applied tothe amplifier 7.

There is also provided a chord detector matrix 9 for detecting the typeof the chord being played on the chord keyboard I by means of the keyswitch 4.

According to this invention, the type of the chord is detected in termsof the root, fifth, major or minor third and major sixth or minorseventh notes. To this end, the chord detector matrix 9 comprises afirst matrix 10 for detecting the root and the fifth notes, a secondmatrix II for detecting the major or minor third note and a third matrix12 for detecting the major six or minor seventh note. Detected outputfrom the first, second and third matrixes I0, 11 and 12 are applied tofirst, second and third bass selectors l3, l4 and 15, respectively. Eachbass selector is applied with the specific bass tone signals from thetone generators 3 corresponding to respective notes contained in thechord being played on the chord keyboard 1. More particularly, the firstbass selector 13 which is connected to receive the control output fromthe first matrix is impressed from the tone generators 3 with pairs ofbass tone signals 13A and 138 corresponding to the root notes and thefifth notes of respective chords being played on the chord keyboard 1.The second bass selector 14 connected to receive the control output fromthe second matrix 11 is applied with bass tone signals 14A correspondingto the major orminor third notes of respective chords. Likewise, thethird bass selector connected to receive the control output from thethird matrix 12 is impressed with bass tone signals 15A corresponding tothe major sixth or minor seventh notes of respective chords.

In the presence of a control output from the first chord detector matrix10, the first bass selector l3 derives from the tone generators 3 basstone signals 13A and 13B corresponding to the root and fifth notes ofthe chord being played and these signals are applied to bass gatecircuits l6 and 17, respectively. Where the played chord contains theminor or major third note, the second detector matrix 11 produces acontrol output, in response to which the second bass selector l4 derivesfrom the tone generators 3 a bass tone signal 14A corresponding to theminor or major third note, which in turn is applied to a third bass gatecircuit 18. Where the played chord contains the major sixth or minorseventh note, the third detector matrix 12 produces a control output, inresponse to which the third bass selector l5 derives from the tonegenerators 3 a base tone signal 15A corresponding to the major sixth orminor seventh note which in turn is applied to a fourth bass gatecircuit 19. The bass selector may preferably have memory functions. Inother words, these bass selectors may be constructed such that theymemorize the types of the chords according to the control output signalsfrom the chord detector matrixes so as to continuously derive out whenthe keys of the chord keyboard are once depressed and then released,bass tone signals corresponding to the played chord until a next otherchord is played.

There is also provided a rhythm pattern pulse generator, generallydesignated by a reference numeral 20, for preparing a timing pulse ofthe desired rhythm pattern to open the chord gate circuit 5 so as toautomatically carry out the desired rhythmic chord performance uponoperation of the chord keyboard 1. The rhythm pattern pulse generatoralso prepares timing pulses to open the bass gate circuits 16 to 19 in aspecific order conforming with the chord performance so as toautomatically carry out the desired rhythmic bass performance with arhythm conforming with the chord performance. The rhythm pattern pulsegenerator 20 comprises a pulse generator 21 which may be an astablemultivibrator having variable oscillation frequencies, a timing pulseencoder 22 connected to receive the output pulse (clock pulse) from thepulse generator 21 for selectively producing a timing pulse sequencehaving a desired rhythm pattern and applied to the chord gate circuit 5,and a pulse distributor 23 connected to receive from the timing pulseencoder 22 a plurality of(for example, three) pulses of varying phasesso as to produce timing pulses which open the bass gate circuits 16through 19 in a predetermined sequence. As will be described later indetail, outputs from the second and third detector matrixes l1 and 12are supplied also to the pulse distributor 23.

The outputs from the bass gate circuits 16 to 19 are applied to theloudspeaker 8 through the tone-coloring filter 24 and the amplifier 7.

Before describing in detail the construction and operation of essentialelements of the electronic organ shown in FIG. 1, the outline of theoperation will first be described. Let us assume that a waltz, a rhumbaor the like is to played. The player plays a chord performance on thechord keyboard 1 in consonance with the melody performance of suchmusic. Such chord performance can be made by intermittently deriving outfrom the chord gate circuit 5 tone signals which are continuouslyapplied to the gate circuit 5 from the tone generators 3 by continuousoperation of the chord keyboard 1 according to a timing pulse sequencehaving a rhythm pattern in consonance with the rhythm of the waltz orrhumba.

When playing a music of waltz, rhumba or beguine wherein bass tones areplayed with three beats per one measure, if a chord [C] were played onthe chord keyboard I, in other words, if the keys corresponding to C, Eand G notes are depressed, the first bass selector 13 will supply a basstone signal of C note corresponding to the root note of the played chordand a bass tone signal of G note corresponding to the fifth note to thegate circuits 16 and 17, respectively, in accordance with the outputfrom the chord detector matrix 9 during the period in which the chordkeyboard 1 is being operated. Further, a bass tone signal of E notecorresponding to the third note of the chord being played is supplied tothe gate circuit 18 from the second bass selector 14. These gatecircuits are opened (rendered conductive) in an order of the first gatecircuit 16, the third gate circuit 18 and the second gate circuit 17 bythe timing pulses from the pulse distributor 23 which is controlled bythe output from the chord detector 9. Thus, the bass performance is madeby three beats in the order or C, E and G notes.

Where a chord [C containing four notes C, E, G and A is to be played,the bass performance is made according to the order of C, A and G.

In this manner, with the novel electronic musical instrument, it is notonly possible to play a chord performance of the desired rhythm but alsoto play a bass performance in consonance with the chord being played,only by continuously depressing the keys of the chord keyboard inconsonance with the melody performance. Furthermore, as above describedas long as the bass selectors have memory functions, it is possible tocontinuously derive out bass tone signals from the bass selectors, untilthe next chord performance is done after the chord keyboard has beenoperated, thus automatically performing the bass performance. In otherwords, it is possible to perform the base performance alone withoutaccompanying the chord performance.

Having completed the brief description regarding the outline of theoperation of the novel electronic musical instrument shown in FIG. 1,the details of essential components thereof will now be described.

FIG. 2 shows a connection diagram of the chord detector matrix 9including, first, second, and third matrixes 10, II and 12. In thisfigure, a group of chord detector key switches is designated by areference numeral 4, the group including at least 12 key switchesrespectively actuated by 12 keys within one octave of the chordkeyboard 1. Key switches 4A to 4L are commonly connected to [2 columnconductors of the first to third matrixes. Column conductors of thefirst matrix 10 (also those of the second and third matrixes) areconnected to the positive terminal (+12V) ofa source respectivelythrough resistors r. Twelve rows or output conductors of the firstmatrix 10 are grounded, respectively, through resistors R. The firstmatrix 10 functions to detect the root and fifth notes of the chordbeing played. There are connected diodes D in the forward direction withrespect to the source voltage between the uppermost output conductor fordetecting the chord [C] and two column conductors connected to the keyswitches 4A and 4H actuated by the keys of the chord keyboard, the keyscorresponding to notes C and G, that is the root and fifth notes ofchord [C]. In the same manner, diodes D,. are connected between anotherone of the output conductors and two column conductors for the purposeof detecting the root and fifth notes in accordance with the type of thechord to be played.

The output conductors of the first matrix 10 are connected tocorresponding output conductors of the second matrix 10 through diodesD,, and D which are connected in series op position as shown in FIG. 2.The positive terminal (+12V) of the source is connected to the juncturesbetween diodes D and D or to the anode electrodes of these diodes D andD respectively, through resistors R. The uppermost output conductor ofthe second matrix 11 is used to detect the major third note E containedin chord [C] and there is connected a diode D between this outputconductor and the column conductor connected to the key switch 4Eactuated by a key of the chord keyboard, corresponding to the note E.

To detect D which is the minor third note of chord [C,,,] comprised bynotes C, D and G, there is connected a diode D, of the polarity shown inthe drawing between the juncture between diodes D and D which areconnected to the lowermost output conductor of the second matrix II andthe uppermost output conductor of the first matrix 10. In the samemanner, diode D is connected between the lower most output conductor ofthe second matrix 11 and the column conductor connected to the keyswitch 4D actuated by a switch corresponding to note D#.

Output conductors of the first matrix are also connected tocorresponding output conductors of the third matrix 12 respectivelythrough diodes D and D connected in series opposition. The juncturesbetween diodes D,.- and D that is the anode electrodes of these diodesare connected to the positive terminal (+l2V) of the source throughrespective resistors R. The uppermost output conductor of the thirdmatrix 12 is used to detect A e.g. the minor seventh note of chord [Ccomprised by notes C, E, and A and there is connected a diode D betweenthis output conductor and a column conductor connected to the key switch4K which is actuated by a key corresponding to note A Furthermore, inorder to detect the note A, that is the major sixth note of chord [Ccomprised by notes C, E, G and A, there is connected a diode D, having apolarity as shown between the juncture between diodes D and D connectedto the lowermost output conductor of the third matrix 12 and theuppermost output conductor of the first matrix 10. There is connected adiode D between the lowermost output conductor of the third matrix 12and a column conductor connected to the key switch 41 actuated by a keycorresponding to note A. Outputs generated on respective outputconductors of the first, second and third matrixes l0, l1 and 12 appearon output terminals 0,, O and 0,.

While the construction of the chord detector matrix 9 shown in FIG. 2has been described with respect to the chord alone related to chord [C],it will be clear to those skilled in the art that the construction forother chords is similar to that described.

The operation of the chord detector matrix will be described hereunderwith reference to FIGS. 3 and 4.

FIG. 3 shows the connection of various component elements with respectto the uppermost output conductor of respective matrixes of the chorddetector matrix 9 shown in FIG. 2. Corresponding elements shown in FIGS.2 and 3 are designated by the same reference characters. The resistancevalues of various resistors are shown by a relationship;

R R r. Where all key switches 4A, 4H, 4E and 4K are opened, in

other words, where keys corresponding to notes C, G, E and A are notdepressed, voltages substantially equal to the source voltage (+l2V).will appear on output terminals 0,, 0 and 0;, of respective matrixes 10,11 and [2. Similar voltages will be obtained when only one of the keyswitches 4A, 4H, 45 and 4K is closed.

When key switches 4A and 4H are closed concurrently, a voltagedetermined by a potentiometer comprised by resistor R and fourparallel-connected resistors R will appear on terminal 0,, the voltagebeing lowered toward ground potential. Since R' R, the positive voltageappearing at terminal 0, at this time is much smaller than the sourcevoltage +l2V whereby the root note and fifth note of the played chordcan be detected. Where key switch 4E is closed while the key switches 4Aand 4H are held closed, a voltage having the same level as thatappearing on terminal 0, will appear on the output terminal 0 of thesecond matrix. In the same manner, closure of key switch 4K provides anoutput voltage on terminal 0 of the third matrix having the same levelas that on terminal Thus, in the ease of chords [C], [C,,,], [C,] andA[C,,] containing C and G as the root and fifth notes, closure of thekey switches 4A and 4H produces a control output (negative spike fromthe +l2-volt level) on terminal 0, connected to the uppermost outputconductor of the first matrix 10. In the case of a chord containing noteE in addition to notes C and G, closure of the key switch 4E willproduce a control output on terminal 0, connected to the uppermostoutput conductor of the second matrix 11. In the case of a chordcontaining note A closure of the key switch 4K produces a control outputon terminal 0 connected to the uppermost output conductor of the thirdmatrix 12.

With reference now to FIG. 4, upon closure of the switches 4A and 4H, acontrol output appears on terminal 0, whereas when the key switch 4E isclosed while the key switches 4A and 4H are held closed, a controloutput appears on terminal This can be noted from the fact that theoutput disappears when the switches 4A and 4H are opened even when theswitch 4E is held closed. Thus, the second and third matrixes I1 and 12of the chord detector matrix 9 depend upon the operation of the firstmatrix 10.

FIG. 5 shows a circuit diagram of one example of the first bass selector13 having a memory function and shown in FIG. 1. The bass selector 13shown comprises a plurality of flip-flop circuits F F F,, correspondingto respective chords to be played, each flip-flop circuit beingcomprised by a pair of transistors T, and T The emitter electrodes oftransistors T, of respective flip-flop circuits are commonly connectedto the positive terminal (+3V of a source, whereas the emitterelectrodes of transistors T are also connected to the same terminalthrough a common feedback impedance element L. The collector electrodesof transistors T, and T are connected to the positive terminal (+15V) ofa source, respectively, through resistors R, and R and resistors R, andR, are provided between the collector electrode of one transistor andthe base electrode of the other transistor. The base electrode oftransistor T is connected to the positive terminal (+3V) of the sourcevia resistor R The control output voltage from the first matrix 10 ofthe chord detector matrix 9 is applied to the base terminals K,, K, K,of respective transistors T, of respective flip-flop circuits through adiode D, with a polarity as shown.

Assuming that flip-flop circuit F, is used to select chord [C], a basstone signal corresponding to the root note C are supplied to thecollector electrode of transistor T, from the tone generators 3 throughserially connected resistor R and diode D,. Also, a bass tone signalcorresponding to the fifth note G is applied to the same collectorelectrode via serially connected resistor R and diode D,.

A resistor R, is connected between the juncture between resistor R anddiode D, and the root note output terminal 0, of the first bass selector13. Similarly, a resistor R, is connected between the juncture betweenresistor R, and diode D and the fifth note output terminal 0 It will beclear that transistors I, of respective flip-flop circuits are normallyconductive because the transistors T are rendered nonconductive by meansof the grounded resistor R As a consequence, the bass tone signalsimpressed upon the collector electrodes of transistors T, is shortcircuited and do not appear on the output terminals 0, and 0 When achord containing notes C and G is played on the chord keyboard 1, acontrol output will appear on the output terminal 0 of the first matrix10, shown in FIG. 2. Since this output impressed upon the base terminalK, of transistor T, of the flip-flop circuit F, has a lower level thanthe emitter voltage (+3V), transistor T, is rendered nonconductive, andhence transistor T is rendered conductive. As the transistor becomesnonconductive, bass tone signals are supplied to the output terminals 0,and 0, and hence to the first and second bass gate circuits l6 and 17.

Thus, the output from the first matrix 10 renders the transistor T, offlip-flop circuit F, nonconductive and the transistor T, conductive.This condition persists even after disappearance of the chord-detectedoutput. This means that the depression of keys of chord keyboard 1corresponding to notes C and G has been memorized. Next upon depressionof a key of the chord keyboard 1 corresponding to notes G and Dcontained in chord [G the first matrix 10 supplies its control output tothe base terminal K of transistor T, of the flip-flop circuit F torender transistor T, nonconductive to provide bass tone signalscorresponding to notes G and D for the output terminals and 0 At thistime the transistor T of that flip-flop circuit is rendered conductive.Upon conduction of transistor T of the flip-flop circuit F a currentflows through the inductor L from its emitter electrode, thereby turningoff the other transistor T which has been conductive and turning ontransistor T which has been nonconductive of the flip-flop circuit F Asabove described, with the bass selector shown in F IG. 5 it is possibleto derive desired bass tone signals from the bass selector and supplythem to the bass gate circuit during a period from an instant when keyscorresponding to notes contained in the chord are depressed once andthen released to an instant at which the next chord is played on thechord keyboard. Accordingly, the player can use his left hand tomanipulate another element of the electronic musical instrument. If theplayer keeps operating the chord keyboard with his left hand, it ispossible to perform both bass performance and chord performance.

The second and third bass selectors l4 and may be constructedidentically to the first bass selector 13, in which case a single basstone signal is impressed on respective flip-flop circuits and thissignal is supplied to bass gate circuits [8 and 19 via single outputterminal.

FIG. 6 shows a circuit diagram of the pulse distributor 23 shown in FIG.1.

Timing pulse encoder 22 supplies three negative pulses P P and P A3 ofdifferent phases corresponding to three beats of rhumba, beguine andwaltz. Pulses P P, and P are impressed upon first, second and third gatecontrol circuits 60, 61 and 62, respectively. Each gate control circuitincludes a monostable multivibrator comprised by transistors T and T anda phase inverter circuit comprised by a transistor T Each multivibratoris constructed such that its transistor T is made normally conductive.Input pulses P P and P,, are impressed upon the collector electrode oftransistors T of respective multivibrators to render the respectivetransistors T nonconductive, thus producing positive pulses P P and P ofa constant pulse width from their collector electrodes. These outputpulses P P and P from the multivibrators are applied to the phaseinverters T to produce negative output pulses P P and P respectively.

Pulse P is impressed upon the first bass gate circuit 16 through a diodewhereas pulses P and P are combined and commonly impressed upon thesecond bass gate circuit 17 through independent diodes.

The output from the c second matrix 11 contained in chord detector 9(see FIG. 1) for detecting the third note and the output from the thirdmatrix 12 for detecting the major sixth or minor seventh note are alsosupplied to the pulse distributor 23. Negative-going output signals fromthe second and third matrixes 11 and 12 are applied to normallyconductive transistors T and T, of the fourth and fifth gate controlcircuits 63 and 64, thus rendering these transistors nonconductive. Uponapplication of the negative-going input signals, the emitter followeroutputs from transistors T and T, are applied to normally conductivetransistors T and T thus rendering them nonconductive. The positiveoutput pulse P from the monostable multivibrator contained in the secondgate control circuit 61 is supplied to the collector electrodes oftransistors T and T The positive pulse P impressed upon the collectorelectrode of transistor T while it is maintained nonconductive isapplied to a shunting transistor T through a series circuit including aresistor and a diode, thus rendering conductive the shunting transistorT which is provided in the circuit with respect to the pulse P includedin the second gate control circuit 61. Thus, the output pulse P isshunted by the transistor T so that it is prevented from being appliedupon the transistor T of the second gate control circuit 61.Consequently, the pulse P is not impressed upon the second bass gatecircuit 17.

The positive pulse P impressed upon the collector electrode oftransistor T while it is maintained nonconductive is impressed upontransistor T and T, through a series circuit including a resistor and adiode thus rendering these transistors conductive. The pulse P impressedupon the collector electrodes of transistors T and T while they aremaintained nonconductive is to be impressed upon the third and fourthbass gate circuits l8 and 19 respectively through phase inverter T and adiode. However, the transistors T, and T are turned on by the positivepulse P which is impressed upon the collector electrode of transistor Twhile it is maintained nonconductive. As a result, negative pulse Pcorresponding to pulse P is applied upon only the fourth bass gatecircuit 19.

With the electronic musical instrument shown in FIG. 1 and comprisingthe pulse distributor just described, when a chord [C], for example, isplayed on the chord keyboard 1, the pulse P from the first gate controlcircuit 60 in response to the pulse P, from timing pulse encoder 22derives a bass tone signal from the first bass gate circuit l6corresponding to the C note which is the root note of the first beat,then the pulse P obtained from the fourth gate control circuit 63 inresponse to the output from the second matrix 11 and the pulse P fromthe timing pulse encoder 22 derives a bass tone signal from the bassgate circuit 18 corresponding to the E note which is the third note ofthe second beat. Thereafter, the pulse P obtained from the third gatecontrol circuit 62 in response to pulse P derives a bass tone signalfrom the second bass gate circuit 17 corresponding to G note which isthe fifth note of the third beat. In this manner, in the case of a chord[C], bass performances are automatically performed in the order of notesC, E and G to produce a music of high quality.

In the case of a chord [C containing notes C, E, G and A as the firstbeat, a bass tone signal corresponding to note C which is the root noteis obtained. As the second beat, the pulse P produced by the fifth gatecontrol circuit 64 by the output from the third matrix 12 in response tothe presence of the note A which is the minor seventh note and the pulseP from the timing pulse encoder 22 derive a bass tone signalcorresponding to note A from the fourth bass gate circuit 19. Thus,where the third note E and the minor seventh note A coexist, apreference is given to the bass tone signal corresponding to the minorseventh note. Then, as the third beat, a bass tone signal of G note,which is the fifth note, is produced. In this manner, in the case of thechord [C the bass performances are done in the order of notes C, A andG. Whereas in the case of a chord performance containing only the rootand fifth notes, or notes C and G the bass performances are done in theorder of notes C, G and G.

In the electronic musical instrument shown in FIG. 1, satisfactory bassperformances are done by controlling the pulse distributor by the outputfrom the chord detector so as to distribute pulses in a most suitableorder among various bass gate circuits impressed with bass tone signals.Instead of controlling the pulse distributor by the chord detector, itis also possible to include suitable means in the distributor that candistribute the pulses among bass gate circuits in an appropriate order.

FIGS. 7 and 8 illustrate such a modified electronic musical instrumentand a modified pulse distributor therefor. Corresponding elements shownin FIGS. 7 and l are designated by the same reference numerals foreliminating duplicated description.

In the modified embodiment shown in FIG. 7 an output pulse I as shown inFIG. 9 is supplied to the timing pulse encoder 22 from the pulsegenerator 21. The timing pulse encoder 22 comprises, for instance, aring counter or a plurality of cascade-connected flip-flop circuits anda plurality of AND circuits to which are applied a plurality ofcombinations of the affirmation outputs and the negation outputs fromrespective flip-flop circuits. In the embodiment shown in FIG. 7 and 8,four AND gate circuits contained in the timing pulse encoder producefour output pulses I,, I,, l and I of different phases as shown in FIG.9 and these output pulses are supplied to distributor 23. Pulses aresupplied to the first through fourth bass gate circuits 16 through 19from distributor 23 in the order of O, to selected by the distributor.

With the pulse distributor shown in FIG. 8, the output pulses I to Ifrom the timing pulse encoder 22 are applied to four input conductors80A, 80B, 80C and 80D of the pulse distributor 23 through capacitors CInput conductors 80A, 80B, 80C and 80D are connected to the positiveterminal (+l2V) of a source respectively through a resistor R Aplurality of output conductor groups 81 to 85 of the numbercorresponding to the number of rhythms desired to be played are providedto cross input conductors 80A to 80D. Each output conductor groupcomprises two to four output conductors and output conductors in eachgroup are connected to the positive terminal (+l2V) of the sourcerespectively through resistors R and rhythm selector switches S S S S,and S provided for respective groups. The juncture between the resistorR of each group of output conductors and a corresponding rhythm selectorswitch is grounded through a parallel circuit comprising a resistor Rand a capacitor C Output conductors in each group are connected torespective output terminals O to 0., of distributor 23 throughcapacitors C output terminals O to 0, being grounded through resistors Rrespectively. At crossing points between output conductors included inrespective groups and connected to respective rhythm selector switches Sto S and input conductors 80A to 800 are connected diodes D according tothe rhythm pattern to be played. With regard to the output conductorgroup 81 connected to rhythm selector switch S diodes D are connected atcrossing points between an output conductor 81A and the input conductor80A, between output conductor 81B and input conductor 80C, and betweenoutput conductor 81C and input conductor 80D, These output conductors81A, 81B and 81C are connected to output terminals 0,, O and 0respectively.

With regard to the output conductor group 85 connected to rhythmselector switch S diodes D are connected at crossing points betweenoutput conductor 85A and input conductor 80A; between output conductor85B and input conductor 80B; between output conductor 85C and inputconductor 80C, and these output conductors 85A, 85B, 85C and 85D areconnected to output terminals 0,, O O and 0,, respectively.

The pulse distributor 23 shown in FIG. 8 operates as follows: whenrhythm selector switches S, to S are opened, as the positive voltage(+l2V) is impressed upon the cathode electrodes of respective diodes D,,these diodes are maintained nonconductive. For this reason, even wheninput pulses I to I are impressed upon input conductors 80A to 80D, nooutput (negative spike) will appear on the output terminals O to 0,.

Then, when rhythm selector switch S for example is closed, the positivevoltage (+l2V) will be impressed upon the anode electrodes of respectivediodes D connected to output conductors 81A, 81B and 81C with the resultthat these diodes are ready to be turned on. Accordingly, when outputpulses I to l as shown in FIG. 9 are applied to input conductors 80A to80D, respectively, from timing pulse encoder 22, output conductors 81A,81B and 81C produce outputs which are differentiated by the action ofcapacitor C and resistor R Differentiated pulses are sequentiallyapplied to the first, third and second bass gate circuits 16, 18 and 17respectively through output terminals 0,, O and 0 as shown in FIG. 7.

FIG. 10A shows output pulses appearing at output terminals 0,, O and 0of pulse distributor 23 when input pulses I, to I, shown in FIG. 9 areapplied and when rhythm selector switch S, is closed, whereas FIG. 108shows the output pulses when rhythm selector switch S is closed.

FIG. 11 shows another embodiment of this invention which ischaracterized by the provision of a chord memory 25. It

should be noted that the drawing is schematically shown as compared withFIG. 1 with respect to the circuitry for bass performance. Moreparticularly, upon operation of chord keyboard 1 the notes of the keysactuated by the output from the chord detector 9 are stored in the chordmemory 25 with the result that the tone signals from the tone generator3 are supplied to the chord gate circuit 5 via chord memory 25 evenafter the operation of the chord performance key has ceased.Accordingly, by the momentary operation of the chord keyboard 1, thetiming pulses from the rhythm pattern pulse generator 20 bring the gatecircuit 5 in the opened state (conducting) according to thepredetermined rhythm pattern thus enabling the desired chord performancewithout the necessity of continuously operating the chord keyboard 1.Also the bass performance is done in the same manner as in theembodiment shown in FIG. 1. FIG. 11, however, shows only one bass memory13 and only one bass gate circuit 16.

The operation of the embodiment shown in FIG. 11 will now be describedwith reference to FIG. 12. Keys on the chord keyboard 1 corresponding tonotes C, E G of the chord [C] are depressed for a short interval so asto store the type of the chord in the memories 25 and 13, by thechorddetected output from the chord detector 9, whereupon tone signalsare supplied to respective gate circuits 5 and 16 from the memories.Since timing pulses are supplied to the gate circuits 5 and 16 from therhythm pattern pulse generator 20 the chord and bass performances asshown in FIG. 12 are performed. More particularly, when the chordkeyboard is operated from a short interval at the beginning of themeasure including a new chord the chord performance and the bassperformance corresponding to the chord [C] will be automaticallyprovided until the chord keyboard is operated next time, that is in theillustrated example, over a period of two measures. In the same manner,when keys corresponding to notes G, B and D contained in a chord [G] aredepressed for a short interval at the beginning of the third measure,the chord and bass performances corresponding to the [G] chord can beprovided.

It is to be understood that the chord memory 25 may be comprised by aplurality of flip-flop circuits in the same manner as the bass selectorshown in FIG. 5.

What is claimed is:

1. An electronic musical instrument comprising tone generators; a chordkeyboard provided with key switches for selectively keying tone signalsfrom said tone generators; a chord detector including first, second andthird detector matrixes responsive to operation of said chord keyboardfor detecting the root and fifth notes, the third note, and the majorsixth or minor seventh note contained in the chord being played on saidchord keyboard and delivering control outputs for corresponding bassnotes; first, second and third bass selectors responsive to said controloutputs from said chord detector matrixes for selectively deriving basstone signals corresponding to respective notes included in the chordfrom said tone generators; a chord gate circuit supplied with tonesignals from said tone generators through the operation of said chordkeyboard; first, second, third and fourth bass gate circuits suppliedwith each bass tone signal corresponding respectively to the root note,fifth note, third note and major sixth or minor seventh note from saidbass selectors; and a rhythm pattern pulse generator coupled to saidchord gate circuit for applying timing pulses to said chord gate circuitfor opening the same in accordance with a predetermined rhythm patternand further coupled to the individual base gate circuits for supplyingtiming pulses to said respective bass gate circuits to open the same ina specific order proper to said chord being played.

2. The electronic musical instrument according to claim 1 wherein eachone of said first, second and third matrixes comprises a plurality ofcolumn conductors and a plurality of output conductors crossing saidcolumn conductors, said plurality of column conductors of each matrixcorresponding to respective notes included in one octave and beingconnected to respective key switches actuated by the keys of said chordkeyboard corresponding to said notes, each one of said column conductorsof said first matrix being connect to a source of voltage via a firstresistor, each one of the output conductors of said first matrix beingconnected to two selected output conductors of said second and thirdmatrixes through a pair of diodes connected in series opposition, eachone of the output conductors of the first matrix being grounded througha second resistor, the juncture between said diodes which are connectedin series opposition being connected to said source of voltage through athird resistor, diodes being connected at two crossing points betweenone output conductor of said first matrix and said plurality of columnconductors, and a diode being connected at a crossing point between eachone output conductor of said second and third matrixes and saidplurality of column conductors, whereby when keys of said chord keyboardare depressed, said key switches corresponding to said depressed keysare closed so as to produce outputs from predetermined output conductorsof said first, second and third matrixes corresponding to respectivenotes contained in respective chords.

3. The electronic musical instrument according to claim 1 wherein eachone of said bass selectors comprises a plurality of flip-flop circuits,each including a normally conductive first transistor and a normallyconductive second transistor, the emitter electrodes of said secondtransistor being connected to a common feedback impedance element, thebase electrode of said first transistor being connected to outputterminal of said chord detector matrix, and the collector electrode ofsaid first transistor being connected to said tone generators whereby abass tone signal is derived from the collector electrode of said firstnormally conductive transistor only when said first transistor isrendered nonconductive in response to the output from said chorddetector.

4. The electronic musical instrument according to claim 1 wherein saidrhythm pattern pulse generator includes a pulse distributor forsupplying timing pulses to said respective bass gate circuits whichcomprises first, second and third gate control circuits suppliedrespectively with pulses of different phases to produce timing pulsesfor controlling said first and second bass gate circuits, the outputs ofsaid second and third gate control circuits being combined, a fourthgate control circuit responsive to the output from said second chord ddetector matrix for preventing application of the timing pulse from saidsecond gate control circuit to second bass gate circuit and forsupplying said timing pulse to said bass gate circuit, and a fifth gatecontrol circuit responsive to the output from said third chord detectormatrix for preventing application of said timing pulse from said secondand fourth gate control circuits to said second and third bass gatecircuits and for supplying said timing pulse to said fourth bass gatecircuit, thereby carrying out bass performance in conformity with thechord being played on said chord keyboard.

5. The electronic musical instrument according to claim 1 wherein saidrhythm pattern pulse generator includes a pulse distributor forsupplying timing pulses to said respective bass gate circuits whichcomprises a plurality of input conductors supplied respectively withpulses of different phases, a plurality of groups of output conductorsof the number corresponding to a plurality of rhythms to be played, aplurality of normally nonconductive diodes which are disposed atcrossing points between output conductors of said respective groups andsaid input conductors in accordance with rhythm pattern corresponding tosaid group of output conductors, and a plurality of rhythm selectorswitches connected to the respective groups of output conductors forrendering conductive the diodes connected to said output conductors,whereby when one of rhythm selector switches is selectively closed, saidtiming pulses are supplied to said respective bass gate circuits fromsaid respective output conductors connected to said closed selectorswitch.

6. The electronic musical instrument according to claim 1 which furtherincludes a chord memory which memorizes respective notes contained in achord in response to respective outputs from said chord detectormatrixes produced by operation of said chord detector matrixes producedby operation of said chord keyboard and applied continuously the tonesignals to said chord gate circuit form said tone generators, therebycarrying out chord performance without necessity of continuouslydepressing the keys of said chord keyboard.

1. An electronic musical instrument comprising tone generators; a chordkeyboard provided with key switches for selectively keying tone signalsfrom said tone generators; a chord detector including first, second andthird detector matrixes responsive to operation of said chord keyboardfor detecting the root and fifth notes, the third note, and the majorsixth or minor seventh note contained in the chord being played on saidchord keyboard and delivering control outputs for corresponding bassnotes; first, second and third bass selectors responsive to said controloutputs from said chord detector matrixes for selectively deriving basstone signals corresponding to respective notes included in the chordfrom said tone generators; a chord gate circuit supplied with tonesignals from said tone generators through the operation of said chordkeyboard; first, second, third and fourth bass gate circuits suppliedwith each bass tone signal corresponding respectively to the root note,fifth note, third note and major sixth or minor seventh note from saidbass selectors; and a rhythm pattern pulse generator coupled to saidchord gate circuit for applying timing pulses to said chord gate circuitfor opening the same in accordance with a predetermined rhythm patternand further coupled to the individual base gate circuits for supplyingtiming pulses to said respective bass gate circuits to open the same ina specific order proper to said chord being played.
 2. The electronicmusical instrument according to claim 1 wherein each one of said first,second and third matrixes comprises a plurality of column conductors anda plurality of output conductors crossing said column conductors, saidplurality of column conductors of each matrix corresponding torespective notes included in one octave and being connected torespective key switches actuated by the keys of said chord keyboardcorresponding to said notes, each one of said column conductors of saidfirst matrix being connect to a source of voltage via a first resistor,each one of the output conductors of said first matrix being connectedto two selected output conductors of said second and third matrixesthrough a pair of diodes connected in series opposition, each one of theoutput conductors of the first matrix being grounded through a secondresistor, the juncture between said diodes which are connected in seriesopposition being connected to said source of voltage through a thirdresistor, diodes being connected at two crossing points between oneoutput conductor of said first matrix and said plurality of columnconductors, and a diode being connected at a crossing point between eachone output conductor of said second and third matrixes and saidplurality of column conductors, whereby when keys of said chord keyboardare depressed, said key switches corresponding to said depressed keysare closed so as to produce outputs from predetermined output conductorsof said first, second and third matrixes corresponding to respectivenotes contained in respective chords.
 3. The electronic musicalinstrument according to claim 1 wherein each one of said bass selectorscomprises a plurality of flip-flop circuits, each including a normallyconductive first transistor and a normally conductive second transistor,the emitter electrodes of said second transistors being connected to acommon feedback impedance element, the base electrode of said firsttransistor being connected to output terminal of said chord detectormatrix, and the collector electrode of said first transistor beingconnected to said tone generators whereby a bass tone signal is derivedfrom the collector electrode of said first normally conductivetransistor oNly when said first transistor is rendered nonconductive inresponse to the output from said chord detector.
 4. The electronicmusical instrument according to claim 1 wherein said rhythm patternpulse generator includes a pulse distributor for supplying timing pulsesto said respective bass gate circuits which comprises first, second andthird gate control circuits supplied respectively with pulses ofdifferent phases to produce timing pulses for controlling said first andsecond bass gate circuits, the outputs of said second and third gatecontrol circuits being combined, a fourth gate control circuitresponsive to the output from said second chord detector matrix forpreventing application of the timing pulse from said second gate controlcircuit to second bass gate circuit and for supplying said timing pulseto said bass gate circuit, and a fifth gate control circuit responsiveto the output from said third chord detector matrix for preventingapplication of said timing pulse from said second and fourth gatecontrol circuits to said second and third bass gate circuits and forsupplying said timing pulse to said fourth bass gate circuit, therebycarrying out bass performance in conformity with the chord being playedon said chord keyboard.
 5. The electronic musical instrument accordingto claim 1 wherein said rhythm pattern pulse generator includes a pulsedistributor for supplying timing pulses to said respective bass gatecircuits which comprises a plurality of input conductors suppliedrespectively with pulses of different phases, a plurality of groups ofoutput conductors of the number corresponding to a plurality of rhythmsto be played, a plurality of normally nonconductive diodes which aredisposed at crossing points between output conductors of said respectivegroups and said input conductors in accordance with rhythm patterncorresponding to said group of output conductors, and a plurality ofrhythm selector switches connected to the respective groups of outputconductors for rendering conductive the diodes connected to said outputconductors, whereby when one of rhythm selector switches is selectivelyclosed, said timing pulses are supplied to said respective bass gatecircuits from said respective output conductors connected to said closedselector switch.
 6. The electronic musical instrument according to claim1 which further includes a chord memory which memorizes respective notescontained in a chord in response to respective outputs from said chorddetector matrixes produced by operation of said chord keyboard andapplied continuously the tone signals to said chord gate circuit formsaid tone generators, thereby carrying out chord performance withoutnecessity of continuously depressing the keys of said chord keyboard.